Applications requiring electric devices operable at Terahertz (THz) frequencies are desirable in many areas such as medical imaging, security detection of hostile objects and noxious chemicals, and others. The THz regime, commonly defined as the range from 300 GHz to 10 THz, corresponds to wavelengths between 1 mm and 30 μm. THz radiation is able to penetrate a variety of materials which are opaque to visible light, such as clothing or paper. On the other hand, THz radiation is absorbed by water and organic substances, materials commonly perceived as transparent. These unique absorption properties lend themselves for various screening and imaging techniques.
A current approach for operating at THz frequencies is based on the use of CMOS technology, more specifically the use of GaAs semiconductor antenna. However, for efficient THz generation in such antenna, employing GaAs photomixer, the laser wavelength has to be smaller than the semiconductor bandgap and the laser sources must be powerful, and as many THz absorption lines are tens or hundreds of GHz broad, must have a large mode-hop-free tuning range. The use of GaAs semiconductor antenna is problematic due to the limit on the speed of electrons in a semiconductor. Therefore the THz range is a spectral gap, in which effective operation of electronics based complex systems are hard to implement.